Numerous prior dispensers are known for dispensing paper towels, kitchen paper, toilet paper, foil, plastics wrapping sheet and other materials wound onto a roll. Usually, such dispensers are provided with a supporting guiding bracket having support members in the form of arms upon each of which an end of an exchangeable roll is rotatably mounted. One of the support arms usually carries a hub member rotatably supported thereon over which one end of the roll core is inserted in replacing the roll. To the other end of the roll, an end plug is secured which is inserted in a retention mechanism in the other support arm of the dispenser. By means of providing an end plug only on one side of the roll, the correct placement of the supply roll relative to the dispensing mechanism and, consequently, the proper feeding of the sheet material is ensured.
In the prior art, different suggestions have been made in order to ensure the proper feeding of dispensers or to prevent the insertion of unauthorized rolls such as paper rolls of inferior quality into a dispenser.
U.S. Pat. No. 2,334,689 deals with the problem of providing dispensers with means to prevent any but a particular type of towel roll being inserted. As a solution to this problem, the paper roll and the paper thereon are provided with a groove at one longitudinal end. Only paper rolls with such a groove can be inserted into the dispenser. If a paper roll without such groove but of shorter longitudinal dimensions is used, it cannot rest on a support structure provided in the dispenser.
EP 0 657 134 B1 provides a solution to the problem of preventing the wrong insertion of paper rolls into a dispenser. The paper rolls are provided with plugs on both sides, the plug on the one side having a larger diameter and a slot which divides the pin into two crescent-shaped segments. This geometry is adapted to match a specific receiving geometry of the dispenser which is provided with corresponding depressions for receiving the crescent-shaped segments of the bearing pin.
Based on the object of preventing unauthorized use of paper rolls, U.S. Pat. No. 2,905,405 describes a coupling mechanism having openings of a special shape within a flange plate of the dispenser. The end plugs of the exchangeable replacement rolls have matching projections to be inserted through these openings. The projections of the end plugs inserted through the openings press on leaf springs that bias them into a position in which they do not impede the proper operation of the dispenser. Only replacement paper rolls having matching projections can be used in order to operate each individual leaf spring.
Another similar technical solution is known from U.S. Pat. No. 6,749,149 B1. The dispenser described therein has support arms for supporting a paper towel roll having a selected geometry with protrusions shaped to fit into matching openings in the end faces of the paper towel roll.
WO 2005/094653 A1 relates to a lock mechanism for a dispenser, an exchangeable roll of material and an end plug therefor and a method for inserting a roll of material into such a lock mechanism. The roll is provided with at least one end plug with a bearing pin for mounting the roll to the lock mechanism of the dispenser. The lock mechanism includes a lock-housing with a guide slot for insertion of the bearing pin, the guide slot having a first section with a first width and a second section with a second width which is smaller than the first width. First and second sections are arranged in a direction perpendicular to the longitudinal extension of the guide slot and in a longitudinal direction of the bearing pin to be received. A sliding element is mounted to the lock housing and movable between a first position closing or narrowing the width of the guide slot and a second position opening the guide slot. A lock element is mounted to the sliding element and rotationally movable around an axis of rotation between a locked position and an unlocked position. The lock element is provided with an engagement portion which, in a locked position, is engaged with a locking geometry of the lock housing.
From WO 2007/065686 A2, a related end plug for a roll of material and retention mechanism in a dispenser are known.
WO 2007/038957 A1 also discloses a related retention mechanism in a dispenser for retaining an exchangeable roll of material.